THE BIOECONOMICS OF RECIRCULATING AQUACULTURE SYSTEMS

The goal of this study was to produce a detailed aquaculture production model incorporating constraints unique to closed system culture and to conduct a formal economic analysis of closed system operation. Results generated by this model indicate that less than perfect management ability can eliminate the normal advantages associated with using high protein feed. While higher protein levels produce faster growth, and for this reason are often used in the industry, the increased direct feed costs and indirect costs due to metabolic feedbacks produce lower daily returns if high protein feed use continues through harvest. This model showed that inefficiency in solids removal negatively affects returns, but the majority of negative impacts were linked to declines in biological filter efficiency. As biological filter efficiency falls, time to harvest increases at an increasing rate and returns decrease at an increasing rate. Results also indicate that as stocking density increased, direct increases in returns were assured only if no metabolic feedbacks occurred. If the filter technology is operated inefficiently, higher stocking density may actually lead to economic failure. Thus, a tradeoff exists between stocking density and management ability, with the tradeoff being substantially affected by levels of dietary protein. In essence, economically viable tradeoffs between dietary protein and stocking density occur over relatively narrow ranges of management ability. Without highly experienced and capable management, the biological realities of recirculating systems may preclude profitable system operation. These simulated observations may in part explain why recirculating systems have yet to demonstrate widespread success on a commercial scale.